U.S. patent number 7,319,724 [Application Number 10/631,655] was granted by the patent office on 2008-01-15 for radio equipment using image signals for compensating transmission signals.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Takahiko Kishi.
United States Patent |
7,319,724 |
Kishi |
January 15, 2008 |
Radio equipment using image signals for compensating transmission
signals
Abstract
Disclosed is radio equipment for transmission and reception of
Frequency Division Duplex mode signals and transmission signal
characteristic compensation utilizing small-scaled circuit
construction. A receiver converts Radio Frequency band signals from
an antenna sharer to an Intermediate Frequency (IF) via a mixer and
into digital signals utilizing an Analog-to Digital Converter.
Reception signals and image signals of transmission signals, both
having an IF A are contained in the converted signals, are
converted into reception signals having an IF B and image signals
having an IF C, respectively, which both have positive and negative
carrier frequencies symmetrical to a zero frequency direct current
component and are represented as a complex number. A transmitter
converts the IF C into a baseband of image signals, and compensates
signal characteristics relative to complex baseband signals of
quantized transmission signals at a characteristic compensator
using converted signals as reference signals.
Inventors: |
Kishi; Takahiko (Yokohama,
JP) |
Assignee: |
Samsung Electronics Co., Ltd.
(KR)
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Family
ID: |
31185103 |
Appl.
No.: |
10/631,655 |
Filed: |
July 31, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040022178 A1 |
Feb 5, 2004 |
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Foreign Application Priority Data
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Aug 5, 2002 [JP] |
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2002-227769 |
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Current U.S.
Class: |
375/297;
455/114.2; 455/114.3; 455/126; 375/296 |
Current CPC
Class: |
H04B
17/14 (20150115); H04B 1/0014 (20130101) |
Current International
Class: |
H04K
1/02 (20060101) |
Field of
Search: |
;375/296,297
;455/114.2,126 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Ghaderis M. et al, "Fast Adaptive Polynomial I and Q Predistorter
with Global Optimisation", IEE Proceedings on Communications, vol.
143, No. 2, Apr. 1, 1996, pp. 78-86. cited by examiner.
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Primary Examiner: Ghayour; Mohammed
Assistant Examiner: Torres; Juan Alberto
Attorney, Agent or Firm: The Farrell Law Firm, PC
Claims
What is claimed is:
1. A radio equipment including at least one compensator for
compensating characteristics of transmission signals, a transmitter
for transmitting the transmission signals, and a receiver for
demodulating reception signals, comprising: at least one
transmission signal distributor for inputting the transmission
signals that the transmitter transmits toward the receiver; and at
least one first frequency converter for converting the reception
signals into reception signals having a first intermediate
frequency including a carrier frequency lower than a carrier
frequency of the reception signals, and for obtaining image signals
of the transmission signals having a carrier frequency around the
first intermediate frequency of the reception signals, wherein the
compensator compensates characteristics of the transmission signals
using characteristics of the image signals.
2. The radio equipment according to claim 1, wherein the
transmission signal distributor comprises an antenna sharer for
inputting the transmission signals toward the receiver as leakage
electrical power.
3. The radio equipment according to claim 2, wherein the antenna
sharer comprises a filter for separating the transmission signals
and the reception signals from each other; wherein the filter is
adjusted to prevent an attenuation pole of the filter from being
positioned within a frequency band of the transmission signals,
thereby enabling a signal pass-through characteristic in the
frequency band of the transmission signals of the filter to have a
substantial horizontal frequency characteristic and a predetermined
attenuation quantity.
4. The radio equipment according to claim 1, wherein the
transmission signal distributor that operates in a Frequency
Duplexing Mode (FDD) mode comprises: a transmission signal
separator for separating a part of electrical power of the
transmission signals; and a mixer for mixing the separated
transmission signals with the reception signals.
5. The radio equipment according to claim 4, wherein the
transmission signal distributor further comprises: an antenna
sharer for inputting the transmission signals toward the receiver
as leakage electrical power; and a switch for connecting the
transmission signal separator with the mixer, wherein, when the
transmission signals are not allowed to obtain sufficient
electrical power from the leakage electrical power of the antenna
sharer, the switch is closed and the transmission signals are input
toward the receiver using the transmission signal separator and the
mixer.
6. The radio equipment according to claim 1, wherein the first
frequency converter is a frequency converter for obtaining real
output signals relative to real input signals.
7. The radio equipment according to claim 1, wherein the first
frequency converter is a frequency converter for obtaining complex
output signals relative to real input signals.
8. The radio equipment according to claim 1, further comprising a
local oscillator for outputting complex local signals at a
frequency equal to the carrier frequency of the image signals, and
at least one second frequency converter for converting the image
signals into a baseband of image signals, wherein the compensator
generates compensation signals for compensating the characteristics
of the transmission signals from the baseband of image signals.
9. A radio equipment including at least one compensator for
compensating characteristics of transmission signals, a transmitter
for transmitting the transmission signals, and a receiver for
demodulating reception signals, comprising: at least one
transmission signal distributor for inputting the transmission
signals that the transmitter transmits toward the receiver; at
least one first frequency converter for converting the reception
signals into reception signals having a first intermediate
frequency including a carrier frequency lower than a carrier
frequency of the reception signals, and for obtaining image signals
of the transmission signals having a carrier frequency around the
first intermediate frequency of the reception signals; and at least
one second frequency converter including a local oscillator for
outputting complex local signals at a frequency equal to the
carrier frequency of the reception signals having the first
intermediate frequency, for converting the reception signals having
the first intermediate frequency into a baseband of signals and for
converting the image signals into image signals having a second
intermediate frequency.
10. The radio equipment according to claim 9, wherein the
compensator generates compensation signals for compensating the
characteristics of the transmission signals from the image signals
having the second intermediate frequency.
11. The radio equipment according to claim 9, wherein the
compensator compensates characteristics of the transmission signals
using characteristics of the image signals.
12. A radio equipment including at least one compensator for
compensating characteristics of transmission signals, a transmitter
for transmitting the transmission signals, and a receiver for
demodulating reception signals, comprising: at least one
transmission signal distributor for inputting the transmission
signals that the transmitter transmits toward the receiver; at
least one first frequency converter for converting the reception
signals into reception signals having a first intermediate
frequency including a carrier frequency lower than a carrier
frequency of the reception signals, and for obtaining image signals
of the transmission signals having a carrier frequency around the
first intermediate frequency of the reception signals; and at least
one second frequency converter including a local oscillator for
outputting complex local signals at a middle frequency between the
carrier frequency of the reception signals having the first
intermediate frequency and the carrier frequency of the image
signals having the first intermediate frequency, for converting the
reception signals having the first intermediate frequency and the
image signals having the first intermediate frequency into
reception signals having a second intermediate frequency and image
signals having a second intermediate frequency, both of which have
positive and negative carrier frequencies symmetrical to a direct
current component having a frequency of zero.
13. The radio equipment according to claim 12, further comprising a
third frequency converter including a local oscillator for
outputting complex local signals at the same frequency as the
carrier frequency of the image signals having the second
intermediate frequency, for converting the image signals having the
second intermediate frequency into a baseband of image signals.
14. The radio equipment according to claim 13, further comprising a
fourth frequency converter, in which complex codomain signals of
the complex local signals of the third frequency converter are used
as local signals of the fourth frequency converter to convert the
reception signals having the second intermediate frequency into the
baseband of signals.
15. The radio equipment according to claim 14, wherein the complex
local signals change the third frequency converter and the fourth
frequency converter, both of which have relations of the complex
codomain with each other, into a synthetic converting means
commonly using the third and fourth converters.
16. The radio equipment according to claim 12, wherein the
compensator compensates characteristics of the transmission signals
using characteristics of the image signals.
Description
PRIORITY
This application claims priority to an application entitled "Radio
Equipment Having Function of Compensating Transmission Signals"
filed in the Japanese Industrial Property Office on Aug. 5, 2002
and assigned Ser. No. 2002-227769, the contents of which are hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to radio equipment, and
more particularly, to radio equipment for compensating electrical
power or characteristics of transmission signals through feedback
of the transmission signals.
2. Description of the Related Art
Such radio equipment, for example, is disclosed in the Japanese
unexamined patent publication No. 1996-223075, in which some
transmission signals transmitted from an antenna are fed back to a
generation circuit of the transmission signals, and thereby levels
or characteristics of the transmission signals are detected. The
levels or characteristics of the transmission signals transmitted
from the antenna are compensated based on the detected levels or
characteristics of the transmission signals.
More specifically, the radio equipment transmits the transmission
signals transmitted from the antenna to the generation circuit of
the transmission signals using a reception circuit to feed back the
transmission signals, so that the transmission circuit and the
reception circuit can be implemented as a very small-scaled circuit
construction.
However, it is disclosed that the foregoing radio equipment simply
uses a reception unit to feed back the transmission signals, but
that transmission and reception signals allowing for the most
effective use of the radio equipment are ones based on the TDD
(Time Division Duplex) mode in which transmission operation does
not concur with reception operation. Further, it is only described
in the document that the radio equipment may be applied to signals
based on the FDD (Frequency Division Duplex) mode in which
transmission operation concurs with reception operation, but that
it is necessary to momentarily stop the reception signals (i.e., to
remove a sound) by means of a certain method in order to measure
characteristics of the transmission signals. However, there is no
disclosure with respect to a concrete method.
Consequently, even though the radio equipment may be applied to the
transmission and reception signals based on the FDD mode, the
conventional radio equipment has a problem in that it cannot
compensate the levels and characteristics of the transmission
signals transmitted from the antenna utilizing a small-scaled
circuit construction.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been designed to solve the
above and other problems occurring in the prior art, and an object
of the present invention is to provide radio equipment capable of
transmitting and receiving signals in an FDD mode, and compensating
characteristics of transmission signals utilizing a small-scaled
circuit.
According to the present invention, the above and other objects can
be accomplished by radio equipment, comprising at least one
compensator for compensating characteristics of transmission
signals; a transmitter for transmitting the transmission signals; a
receiver for demodulating reception signals, comprises; at least
one transmission signal distributor for inputting the transmission
signals which the transmitter transmits toward the receiver; at
least one first frequency converter for converting the reception
signals into reception signals having a first intermediate
frequency (IF) including a carrier frequency lower than a carrier
frequency of the reception signals, and for obtaining image signals
of the transmission signals having a carrier frequency around the
first IF of the reception signals, wherein the compensator
compensates characteristics of the transmission signals using
characteristics of the image signals.
Thus, the radio equipment converts the reception signals into
reception signals having a first IF including a carrier frequency
lower than a carrier frequency of the reception signals, and at the
same time extracts the transmission signals, which are obtained on
the side of the receiver by the transmission signal distributor, as
the image signals of the transmission signals having the carrier
frequency around the first IF of the reception signals, by means of
the first frequency converter. In addition, the compensator
compensates characteristics of the transmission signals using
characteristics of the image signals, so that without an additional
circuit construction for extracting separate transmission signals,
the characteristics of the transmission signals can be indirectly
detected on the side of the receiver, and the detected
characteristics can be used to compensate the characteristics of
the transmission signals.
The transmission signal distributor includes an antenna sharer for
inputting the transmission signals toward the receiver as leakage
electrical power. Therefore, the radio equipment uses the
transmission signal distributor as the antenna sharer for
transmitting and receiving the transmission and reception signals
to/from the same antenna, so that the transmission signals can be
input toward the receiver as leakage electrical power of the
antenna sharer without an additional new circuit construction.
The antenna sharer includes a filter for separating the
transmission signals and the reception signals from each other.
Further, the filter is adjusted to prevent an attenuation pole of
the filter from being positioned within the frequency band of the
transmission signals even though a pass frequency band of passing
from the transmitter-sided input terminal of the antenna sharer to
the receiver-sided output terminal is a stop band of the filter,
and thus a signal pass-through characteristic in the frequency band
of the transmission signals of the filter has a substantial
horizontal frequency characteristic and a predetermined attenuation
quantity. Therefore, the radio equipment adjusts the pass frequency
band of passing from the transmitter-sided input terminal of the
antenna sharer to the receiver-sided output terminal, even though
the pass frequency band is the stop band of the filter for
separating the transmission and reception signals from each other,
so as to prevent the attenuation pole of the filter from being
positioned within the frequency band of the transmission signals.
The filter makes it possible to stably obtain the transmission
signals on the side of the receiver owing to the characteristics
having the substantial horizontal frequency characteristic and the
predetermined attenuation quantity in the frequency band of the
transmission signals.
The transmission signal distributor comprises a transmission signal
separator for separating a part of electrical power of the
transmission signals, and a mixer for mixing the separated
transmission signals with the reception signals. Therefore, the
radio equipment uses the transmission signal distributor as the
transmission signal separator for separating a part of electrical
power of the transmission signals and the mixer for mixing the
separated transmission signals with the reception signals, so that
the transmission signals can be certainly input toward the
receiver.
The transmission signal distributor comprises an antenna sharer for
inputting the transmission signals toward the receiver as leakage
electrical power, a transmission signal separator for separating a
part of electrical power of the transmission signals, a mixer for
mixing the separated transmission signals with the reception
signals, and a switch for connecting the transmission signal
separator with the mixer. Therefore, when the transmission signals
are not allowed to obtain sufficient electrical power from the
leakage electrical power of the antenna sharer, the switch is
closed, and then the transmission signals are input toward the
receiver using the transmission signal separator and the mixer.
The radio equipment comprises the transmission signal separator for
separating a part of electrical power of the transmission signals
and the mixer for mixing the separated transmission signals with
the reception signals together with the antenna sharer for
transmitting and receiving the transmission and reception signals
to/from the same antenna, all of which act as the transmission
signal distributor. When a frequency characteristic is bad on a
communication band edge or when the leakage electrical power of the
antenna sharer is small due to an available frequency band in
multi-band radio equipment, the switch is closed, and then the
transmission signals are obtained at a proper level using the
transmission signal separator and the mixer. In the other cases,
the transmission signals are obtained at a proper level using the
transmission signal separator and the mixer. Under any
circumstance, the transmission signals are input to the receiver at
a proper level.
The first frequency converter is a frequency converter for
obtaining real output signals relative to real input signals.
Therefore, the radio equipment can obtain the image signals of the
transmission signals at a sufficient level. Further, the first
frequency converter is a frequency converter for obtaining complex
output signals relative to real input signals. Therefore, the radio
equipment can obtain the image signals of the transmission signals
at a level without having influence on the reception signals. For
example, when the radio equipment, in which transmission signal
waves and reception signal waves are easily separated from each
other, are overlapped with each other at a frequency of the same
carriers, as signals based on a CDMA (Code Division Multiple
Access) or TDD mode, the reception signals and the image signals of
the transmission signals, both of which have the first IF, are
extracted at the same frequency, so that the number of times for
performing frequency conversion can be reduced in the following
processes.
The radio equipment further comprises a second frequency converter
provided with a local oscillator for outputting complex local
signals at a frequency equal to the carrier frequency of the
reception signals having the first IF, for converting the reception
signals having the first IF into a baseband of signals and for
converting the image signals into image signals having the second
IF. Thus, the compensator generates compensation signals for
compensating the characteristics of the transmission signals from
the image signals having the second IF.
When compensating only the level of the transmission signals, the
radio equipment provides a preferential process of the reception
signals and detects a change in the level of the transmission
signals from the image signals having the IF as it is, and thereby
the compensator compensates the level of the transmission signal.
As a result, the radio equipment can remove a process in which the
transmission signals are changed into a baseband.
The radio equipment may further comprise at least one second
frequency converter, provided with a local oscillator for
outputting complex local signals at a frequency equal to the
carrier frequency of the image signals, for converting the image
signals into a baseband of image signals. Thus, the compensator
generates compensation signals for compensating the characteristics
of the transmission signals from the baseband of image signals.
When compensating all signal characteristics including distortion
of the transmission signals, the radio equipment separately
prepares a frequency converter for the reception signals, provides
a preferential process of the reception signals, changes the image
signals of the transmission signals into a baseband, and detects
the changed signals, and thereby enabling the compensator to
compensate the characteristics of the transmission signals. As a
result, the radio equipment reduces the number of times for
performing frequency conversion when obtaining the characteristics
of the transmission signals and exactly compensates the signals
characteristics including a level or distortion of the transmission
signals.
The radio equipment comprises at least one second frequency
converter, provided with a local oscillator for outputting complex
local signals at the middle frequency between the carrier frequency
of the reception signals having the first IF and the carrier
frequency of the image signals having the first IF, for converting
the reception signals and the image signals, both of which have the
first IF, into reception signals having the second IF and for
converting image signals having the second IF, respectively, both
of which have positive and negative carrier frequencies symmetrical
to a direct current component having a frequency of zero; and a
third frequency converter, provided with a local oscillator for
outputting complex local signals at the same frequency as the
carrier frequency of the image signals having the second IF, for
converting the image signals having the second IF into a baseband
of image signals. Thus, the compensator generates compensation
signals for compensating the characteristics of the transmission
signals from the baseband of image signals.
The radio equipment converts the reception signals and the image
signals, both of which have the first IF, into the reception
signals and the image signals, respectively, both of which have the
second IF and positive and negative carrier frequencies symmetrical
to the direct current component having the frequency of zero,
changes the image signals of the transmission signals into a
baseband and extracts signal characteristics of the changed
results, in order to process the reception signals with ease.
Thereby, the compensator compensates the characteristics of the
transmission signals. Thus, the signal characteristics including a
level or distortion of the transmission signals can be exactly
compensated, and at the same time, a transmitter-sided circuit
construction can be balanced with a circuit construction on the
side of processing the transmission signals.
Further, the radio equipment further comprises a fourth frequency
converter, in which complex codomain signals of the complex local
signals of the third frequency converter is used as local signals
of the fourth frequency converter in order to convert the reception
signals having the second IF into a baseband of signals. Therefore,
the radio equipment causes both the complex local signals of the
frequency converter on the side of processing the transmission
signals and the complex local signals of the frequency converter on
the side of the receiver to have relations of a complex codomain
with each other, so that only by inverting a sign of imaginary-axis
signals of the complex local signals on one side, complex local
signals can be generated on the other side.
Preferably, the complex local signals are allowed to change the
third frequency converting means and the fourth frequency
converting means, both of which have relations of the complex
codomain with each other, into a synthetic converting means
commonly using the third and fourth converting means. Thus, the
radio equipment enables the circuit construction needed for the
frequency converters (i.e., a multipliers in the case of processing
digital signals) to be shared.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features, and advantages of the
present invention will be more apparent from the following detailed
description taken in conjunction with the accompanying drawings, in
which:
FIG. 1 is a block diagram illustrating radio equipment for
compensating transmission signals according to a first example of a
first embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating an arrangement of
transmission and reception signals on a frequency axis in the first
example of the first embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a level of transmission
signals obtained on the side of a receiver in the first example of
the first embodiment of the present invention;
FIG. 4 is a block diagram illustrating radio equipment for
compensating transmission signals according to a second example of
the first embodiment of the present invention;
FIG. 5 is a block diagram illustrating radio equipment for
transmission signals according to a third example of the first
embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating an arrangement of
transmission and reception signals on a frequency axis in the third
example of the first embodiment of the present invention;
FIG. 7 is a block diagram illustrating radio equipment for
compensating transmission signals according to a fourth example of
the first embodiment of the present invention;
FIG. 8 is a schematic diagram illustrating an arrangement of
transmission and reception signals on a frequency axis in the
fourth example of the first embodiment of the present
invention;
FIG. 9 is a block diagram illustrating radio equipment for
compensating transmission signals according to a first example of a
second embodiment of the present invention;
FIG. 10 is a schematic diagram illustrating a level of transmission
signals obtained on the side of a receiver in the first example of
the second embodiment of the present invention;
FIG. 11 is a block diagram illustrating radio equipment for
compensating transmission signals according to a first example of a
third embodiment of the present invention;
FIG. 12 is a schematic diagram illustrating a level of transmission
signals obtained on the side of a receiver in the first example of
the third embodiment of the present invention;
FIG. 13 is a block diagram illustrating radio equipment for
compensating transmission signals according to a first example of a
fourth embodiment of the present invention; and
FIG. 14 is a schematic diagram illustrating a level of transmission
signals obtained on the side of a receiver in the first example of
the fourth embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, preferred embodiments of the present invention will be
described in detail with reference to the accompanying drawings.
Above all, it should be noted that similar parts are given
reference numerals and symbols as similar as possible throughout
the drawings. In the following description, numerous specific
details are set forth, such as specific circuit components, etc.,
to provide a thorough understanding of the present invention.
However, it will be obvious to those skilled in the art that the
present invention may be practiced without such specific details.
In the description of the present invention, a detailed description
of known functions and configurations incorporated herein will be
omitted when it may make the subject matter of the present
invention rather unclear.
I. First Embodiment
A. First Example of the First Embodiment
FIG. 1 is a block diagram illustrating radio equipment for
compensating transmission signals according to a first example of a
first embodiment of the present invention. With reference to FIG.
1, the radio equipment, which is provided with a receiver 1 for
receiving signals transmitted from counterpart radio equipment and
a transmitter 2 for transmitting signals to the counterpart radio
equipment, includes an antenna 3 for transmitting and receiving the
signals to/from the counterpart radio equipment, and an antenna
sharer 4, such as a duplexer, circulator or the like, enabling the
receiver 1 and the transmitter 2 to make common use of the antenna
3 and to transmit and receive the signals to/from the counterpart
radio equipment.
Further, the antenna sharer 4 includes an antenna connection
terminal 4x for connecting with the antenna 3, a receiver-sided
output terminal 4y for connecting with the receiver 1, and a
transmitter-sided input terminal 4z for connecting with the
transmitter 2. The antenna sharer 4 outputs a reception signal band
of signals, which are input into the antenna connection terminal
4x, to the receiver-sided output terminal 4y, and outputs a
transmission signal band of signals, which are input into the
transmitter-sided input terminal 4z, to the antenna connection
terminal 4x.
The receiver 1 amplifies an RF (Radio Frequency) band of signals
input from the receiver-sided output terminal 4y of the antenna
sharer 4 using an LNA (Low Noise Amplifier) 11, filters the RF band
of signals amplified by the LNA 11 using a reception filter 12, and
extracts signals having a predetermined frequency band including
the transmission signal band and the reception signal band. To
extract signals having a desired carrier frequency from the
predetermined frequency band of signals, which the reception filter
12 outputs, and quantize (i.e., carry out A/D conversion of) the
extracted signals, a mixer 14 converts a predetermined frequency
band of signals into signals having a first intermediate frequency
(IF A) using the local signals which a carrier oscillator 13
outputs at a first frequency, and a low-pass filter 15 imposes band
limitations on the signals, which the mixer 14 outputs, at a
frequency less than half of a sampling frequency for
quantization.
When the signals output from the mixer 14 are band-limited by the
low-pass filter 15, the receiver 1 converts the signals
band-limited by the low-pass filter 15 into digital ones, using an
ADC (A/D converter) 16 for quantizing input signals at the sampling
frequency corresponding to a bandwidth of the low-pass filter 15
according to the sampling theorem.
A GCA (Gain Control Amp.) 17, which maintains output signals at a
uniform level by controlling a degree of amplification to amplify
input signals, converts the quantized signals output from the ADC
16 into a uniform level of signals.
Further, the receiver 1 converts reception signals and image
signals of transmission signals, both of which have the IF A and
are contained in the signals output from the digital GCA 17, into
reception signals having an IF B and image signals having an IF C,
both of which have positive and negative carrier frequencies
symmetrical to a direct current component having a frequency of
zero and are represented as a complex number, by a quadrature
detector 18 having a quadrature carrier oscillator for outputting
complex local signals at a second frequency located at the middle
of respective carrier frequency of the reception signals and the
image signals of the transmission signals.
The reception signals having the IF B are converted into a baseband
of reception signals by a frequency converter 19 having a
quadrature carrier oscillator for outputting complex local signals
having a third frequency, which is equal to a carrier frequency of
the reception signals having the IF B.
Further, an amplification degree of the digital GCA 17 is
controlled by an AGC (Auto Gain Control) circuit 20 that detects a
level of the reception signals from the baseband of reception
signals converted by the frequency converter 19, and by feeding the
detected level back to the digital GCA 17 to uniformly maintain the
reception signal level.
The quadrature detector 18 includes a quadrature carrier oscillator
1a for outputting complex local signals at a second frequency
located at the middle of respective carrier frequency of the
reception signals and the image signals of the transmission
signals, both of which have the IF A and are output from the
digital GCA 17, a multiplier 1b for multiplying real signals, which
the digital GCA 17 outputs, by real-axis signals "cos" of local
signals which the quadrature carrier oscillator 1a outputs at the
second frequency, and a multiplier 1c for multiplying real signals,
which the digital GCA 17 outputs, by imaginary-axis signals "-sin",
which have a phase forwarded by 90 degrees relative to that of the
real-axis signals. The quadrature detector 18 gets complex number
signals by performing orthogonal transformation to the real signals
output from the digital GCA 17.
The frequency converter 19 includes the quadrature carrier
oscillator 2a for outputting complex local signals having a third
frequency, which is equal to a carrier frequency of the reception
signals having the IF B, multipliers 2b and 2c for multiplying real
and imaginary-axis signals of the complex signals, which the
quadrature detector 18 outputs, by real-axis signals "cos" of the
local signals which the quadrature carrier oscillator 2a outputs at
the third frequency, and by imaginary-axis signals "-sin", which
have a phase forwarded by 90 degrees relative to that of the
real-axis signals, respectively, a subtracter 2d for subtracting
outputs of the multiplier 2c from outputs of the multiplier 2b and
taking the subtracted results as outputs of the real-axis signals,
multipliers 2e and 2f for multiplying real and imaginary-axis
signals of the complex signals, which the quadrature detector 18
outputs, by imaginary-axis signals "-sin" and real-axis signals
"cos", respectively, of the local signals which the quadrature
carrier oscillator 2a outputs at the third frequency, and an adder
2g for adding outputs of the multiplier 2f to outputs of the
multiplier 2e and taking the added results as outputs of the
imaginary-axis signals. The frequency converter 19 converts the
reception signals having the IF B, which are output from the
quadrature detector 18, into the baseband of reception signals.
The transmitter 2 converts the image signals, which the quadrature
detector 18 outputs at an IF C, into the baseband of image signals,
utilizing the frequency converter 21, which takes complex codomain
signals of the complex local signals, which the quadrature carrier
oscillator 2a of the frequency converter 19 outputs at the third
frequency, as local signals having a fourth frequency.
Using the baseband image signals, which are generated by the
transmission signals transmitted from the antenna 3 and
simultaneously converted into the baseband of signals by the
frequency converter 21, as reference signals, a characteristic
compensator 22 compensates signal characteristics, for example, in
a manner that the transmission signals transmitted from the antenna
3 endow complex baseband signals of the quantized transmission
signals with an inverse characteristic of phase or amplitude
distortion which is applied to an amplifier (Amp) and so forth in
the following processes.
To transmit the characteristic-compensated transmission signals,
which the characteristic compensator 22 outputs, from the antenna
3, the complex baseband signals of the transmission signals are
converted into transmission signals, which have an IF D and are
represented as real signals, by a quadrature modulator 23 having a
quadrature carrier oscillator for outputting complex local signals
having a fifth frequency.
The transmitter 2 also converts the transmission signals, which are
output from the quadrature modulator 23 at the IF D and are
represented as quantized real signals, into analog transmission
signals having the IF D by means of a DAC (D/A converter) 24 for
converting input quantization signals into analog signals by
performing D/A conversion. In order to transmit the analog
transmission signals, which the DAC 24 outputs, from the antenna 3,
the transmitter 2 converts the transmission signals having the IF D
into transmission signals having a frequency of the transmission
signal band utilizing a mixer 26 using the local signals which the
carrier oscillator 13 outputs at the first frequency.
Additionally, an analog GCA (Gain Control Amplifier) 27, which
controls a degree of amplification to amplify the input signals and
maintains output signals at a uniform level, converts the
transmission signals, which the mixer 26 outputs at the frequency
of the transmission signal band, into signals having a uniform
level. Subsequently, a PA (Power Amplifier) 28 amplifies the
transmission signals having the frequency of the transmission
signal band, which are controlled at a uniform level by the analog
GCA 27, into a high level of signals for transmission from the
antenna 3. Further, outputs of the PA 28 are sent from the
transmitter-sided input terminal 4z of the antenna sharer 4
connected to the PA 28 through the antenna connection terminal 4x
to the antenna 3, and thus transmitted to counterpart radio
equipment.
Similar to the characteristic compensator 22, the amplification
degree of the analog GCA 27 is controlled by an ALC (Auto Level
Control) circuit 29 that detects a mean level of the transmission
signals transmitted from the antenna 3, and then by feeding the
mean level back to the analog GCA 27 to uniformly maintain the mean
level, with the use of the baseband image signals output from the
frequency converter 21 as reference signals.
As for the frequency converter 21, in order to obtain the complex
codomain signals having the third frequency of complex local
signals, which the quadrature carrier oscillator 2a of the
frequency converter 19 outputs, the frequency converter 21 includes
a sign inverter 3a for inverting signs of the imaginary-axis
signals which the quadrature carrier oscillator 2a outputs,
multipliers 3b and 3c for multiplying real and imaginary-axis
signals of the complex signals, which the quadrature detector 18
outputs, by real-axis signals "cos" of the local signals which are
output from the quadrature carrier oscillator 2a at the fourth
frequency and generated from the local signals having the third
frequency, and by imaginary-axis signals "sin" which have a phase
delayed by 90 degrees relative to of the real-axis signals,
respectively, a subtracter 3d for subtracting outputs of the
multiplier 3c from outputs of the multiplier 3b and taking the
subtracted results as outputs of the real-axis signals, multipliers
3e and 3f for multiplying real and imaginary-axis signals of the
complex signals, which the quadrature detector 18 outputs, by
imaginary-axis signals "sin" and real-axis signals "cos",
respectively, of the local signals which are output from the
quadrature carrier oscillator 2a at the fourth frequency and
generated from the local signals having the third frequency, and an
adder 3g for adding outputs of the multiplier 3f to outputs of the
multiplier 3e and taking the added results as outputs of the
imaginary-axis signals. The frequency converter 21 converts the
image signals having the IF C, which the quadrature detector 18
outputs, into a baseband reception signals.
Further, the quadrature modulator 23 includes a quadrature carrier
oscillator 4a for outputting the fifth frequency of complex local
signals, a multiplier 4b for multiplying real-axis signals, which
the characteristic compensator 22 outputs, by real-axis signals
"cos" in the fifth frequency of local signals which the quadrature
carrier oscillator 4a outputs, a multiplier 4c for multiplying
imaginary-axis signals, which the characteristic compensator 22
outputs, by imaginary-axis signals "sin" which have a phase delayed
by 90 degrees relative to that of the real-axis signals "cos" in
the fifth frequency of local signals which the quadrature carrier
oscillator 4a outputs, and a subtracter 4d for subtracting outputs
of the multiplier 4c from outputs of the multiplier 4b and taking
the subtracted results as outputs of the real-axis signals. The
quadrature modulator 23 converts the complex baseband signals of
the transmission signals into the transmission signals having the
IF D and represented as the imaginary signals.
To perform frequency conversion of both the reception signals and
the transmission signals at the mixer 14 and the mixer 26,
respectively, using the local signals, which the carrier oscillator
13 outputs at the first frequency, a difference between the
reception signal band and the transmission signal band when the
transmission and reception signals are ones based on the FDD mode,
is absorbed by a difference between the frequency of the local
signals from the quadrature carrier oscillator 1a used in the
quadrature detector 18 and the frequency of the local signals from
the quadrature carrier oscillator 4a used in the quadrature
modulator 23.
Subsequently, using the radio equipment of the present embodiment
for compensating transmission signals as described above, a
detailed description will be made with reference to a schematic
diagram regarding a structure in which transmission signals
transmitted from the antenna 3 are input as reference signals into
the characteristic compensator 22 and the ALC circuit 29.
FIG. 2 is a schematic diagram for describing a structure in which
transmission signals transmitted from the antenna 3 are obtained as
reference signals in the characteristic compensator 22, and
illustrates transmission signals having a frequency of 835 [MHz],
reception signals having a frequency of 870 [MHz], and local
signals output from the carrier oscillator 13 having a first
frequency of 848.5 [MHz].
In FIG. 1, the transmission signals, which are output from the PA
28 of the transmitter 2 at a carrier frequency of 835 MHz, are
mostly transmitted from the transmitter-sided input terminal 4z of
the antenna sharer 4 through the antenna connection terminal 4x to
the antenna 3 and then to the counterpart radio equipment, but can
be partially detected as leakage electrical power at the
receiver-sided output terminal 4y of the antenna sharer 4.
As illustrated in FIG. 2(a), when the transmission signals are
input into the mixer 14 at a carrier frequency of 835 MHz and when
the reception signals are input into the mixer 14 at a carrier
frequency of 870 MHz, both of the transmission and reception
signals are frequency-converted by the local signals which the
carrier oscillator 13 outputs at a frequency of 848.5 MHz, so that
reception signals of an IF of 21.5 MHz and image signals of an IF
of 13.5 MHz generated from the transmission signals are output from
the mixer 14, as illustrated in FIG. 2(b). Further, when the
reception signals of the IF of 21.5 MHz and the image signals of
the IF of 13.5 MHz generated from the transmission signals are
input into the quadrature detector 18 in which the complex local
signals output from the quadrature carrier oscillator 1a are set to
have a frequency of 17.5 MHz, reception signals of an IF of 4.0 MHz
and the image signals of an IF of -4.0 MHz, both of which are
located at a position symmetrical to a direct current component
having a frequency of zero, are output as outputs of the quadrature
detector 18, as illustrated in FIG. 2(c). Therefore, the reception
signals of the IF of 4.0 MHz can be converted into baseband
reception signals by the frequency converter 19 in which the
quadrature carrier oscillator 2a outputs the complex local signals
at a frequency of 4.0 MHz.
Further, by the frequency converter 21 in which complex signals of
a frequency of -4.0 MHz, which are generated as complex codomain
signals of the complex local signals output from the quadrature
carrier oscillator 2a, are used as local signals, the image signals
having the IF C can be converted into a baseband of image
signals.
Here, for example, when the antenna sharer 4 is used as a duplexer,
in terms of a frequency characteristic around 870 MHz in the
duplexer, even though a pass frequency band of passing from the
transmitter-sided input terminal 4z of the duplexer to the
receiver-sided output terminal 4y is, for example, a stop band of a
filter having an attenuation quantity of 35 [dB], it is preferable
that an attenuation pole of the filter is adjusted not to be
positioned within the frequency band of the transmission signals,
and that a signal pass characteristic in the frequency band of the
transmission signals of the filter has a substantial horizontal
frequency characteristic and a predetermined attenuation quantity
(e.g., the foregoing attenuation quantity of 35 [dB]), and thereby
the transmission signals can be input toward the receiver 1 without
any distortion.
Additionally, in the present embodiment, when a level of the image
signals of the transmission signals is calculated at the output of
the mixer 14, as shown in the schematic diagram of FIG. 3, for
example, when the transmission signals transmitted from the antenna
3 has a level of 0 [dBm], the antenna sharer (duplexer) 4 has a
leakage electrical power attenuation quantity of 35 [dB], the LNA
11 and the reception filter 12 have the total gain of 6 [dB], the
mixer 14 has a gain of 3 [dB], and the image signals of the mixer
14 has a suppressed level of 0 [dB], the level of the image signals
of the transmission signals at the output of the mixer 14 is
obtained by the following Equation 1.
Equation 1 0 [dBm]-35 [dB]+6 [dB]+3 [dB]-0 [dB]=-26 [dB] (1)
As described above, the first example of the first embodiment is
designed to extract the image signals of the transmission signals
at a sufficient level and simultaneously to process the reception
signals with ease using the mixer 14, in such a manner that the
quadrature detector 18 converts the reception signals and image
signals, both of which are extracted at the first IF, into the
reception signals having the second IF and the image signals having
the second IF, respectively, both of which have positive and
negative carrier frequencies symmetrical to the direct current
component having a frequency of zero, that the frequency converter
21 causes the image signals of the transmission signals to become
an image band and then extracts a signal characteristic of the
image signals of the transmission signals, and thereby the
characteristic compensator 22 compensates a characteristic of the
transmission signals. Thus, signal characteristics including a
level or distortion of the transmission signals can be exactly
compensated, and at the same time a transmitter-sided circuit
construction can be balanced with a circuit construction on the
side of processing the transmission signals.
B. Second Example of the First Embodiment
FIG. 4 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a second
example of the first embodiment of the present invention. In FIG.
4, the radio equipment is characteristic of the radio equipment
which was described in the first example of the first embodiment.
In particular, the radio equipment modifies both the frequency
converter 19 on the side of the receiver 1 and the frequency
converter 21 on the side of the transmitter 2 into a synthetic
frequency converter 30, which commonly uses of the multipliers.
Further, in FIG. 4, components having the same reference numeral
and symbol as in the first example of the first embodiment perform
the same operation as ones mentioned in the first example of the
first embodiment, and thus their description is omitted here.
With reference to FIG. 4, the radio equipment converts both
reception signals and image signals of transmission signals, both
of which a digital GCA 17 outputs at an IF A, into reception
signals having an IF B and image signals having an IF C,
respectively, by means of a quadrature detector 18, wherein the
quadrature detector 18 is provided with a quadrature carrier
oscillator for outputting complex local signals at a second
frequency located at the middle of a carrier frequency which the
reception signals and the other image signals of transmission
signals each have, and wherein the reception signals having the IF
B and the image signals having the IF C have positive and negative
carrier frequencies symmetrical to a direct current component
having a frequency of zero and are represented as complex numbers
at the same time.
By a synthetic frequency converter 30 provided with the quadrature
carrier oscillator for outputting complex local signals having a
third frequency equal to a carrier frequency of the reception
signals having the IF B, the reception signals having the IF B are
converted into a baseband of reception signals, and at the same
time the image signals having the IF C are converted into a
baseband of image signals. The baseband of image signals are then
input into a characteristic compensator 22 and an ALC circuit
29.
The synthetic frequency converter 30 includes a quadrature carrier
oscillator 5a for outputting complex local signals having a third
frequency, multipliers 5b and 5c for multiplying real-axis signals
and imaginary-axis signals, both of which are input from a
quadrature detector 18, by real-axis signals and imaginary-axis
signals respectively, both of which the complex local signals
generated from the quadrature carrier oscillator 5a have, and an
adder 5e for causing a sign of outputs of the multiplier 5c to be
inverted by a sign inverter 5d, adding the inverted outputs of the
multiplier 5c to outputs of the multiplier 5b, and taking the added
results as real-axis signal outputs of the reception signals
contained in two kinds of real-axis signal outputs.
Further, the synthetic frequency converter 30 includes multipliers
5f and 5g for similarly multiplying real-axis signals and
imaginary-axis signals, both of which are input from a quadrature
detector 18, by real-axis signals and imaginary-axis signals,
respectively, both of which the complex local signals generated
from the quadrature carrier oscillator 5a have, and an adder 5h for
adding outputs of the multiplier 5g to outputs of the multiplier 5f
and taking the added results as imaginary-axis signal outputs of
the reception signals contained in two kinds of imaginary-axis
signal outputs.
Additionally, the synthetic frequency converter 30 includes an
adder 5i for adding outputs of the multiplier 5c to outputs of the
multiplier 5b and taking the added results as real-axis signal
outputs of the image signals contained in two kinds of real-axis
signal outputs, and an adder 5k for causing an output sign of the
multiplier 5f to be inverted by a sign inverter 5j, adding the
inverted outputs of the multiplier 5f to outputs of the multiplier
5g, and taking the added results as imaginary-axis signal outputs
of the image signals contained in two kinds of imaginary-axis
signal outputs. Thus, the synthetic frequency converter 30 does not
only convert the reception signals having the IF B into a baseband
of reception signals, but also convert the image signals having the
IF C into a baseband of image signals.
As described above, in the second example of the first embodiment,
both the frequency converter 19 on the side of the receiver 1 and
the frequency converter 21 on the side of the transmitter 2 in the
radio equipment having a function of compensating transmission
signals which has been described in the first example of the first
embodiment, are modified into a synthetic frequency converter 30
constructed to make common use of multipliers of the converters 19
and 21, so that the radio equipment according to the second example
of the first embodiment can simplify its circuit construction, thus
reducing its circuit dimensions and saving its space as well as its
electrical power.
C. Third Example of the First Embodiment
FIG. 5 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a third
example of the first embodiment of the present invention. In FIG.
5, the radio equipment is characterized in that the frequency
converter 21 on the side of the transmitter 2 of the radio
equipment which has been described in the first example of the
first embodiment has been omitted, the frequency converter 19 on
the side of the receiver 1 is provided with a quadrature carrier
oscillator 6a for outputting complex local signals having a sixth
frequency equal to the carrier frequency of the image signals of
the transmission signals which the digital GCA 17 outputs, instead
of the quadrature carrier oscillator 1a for outputting the complex
local signals having the second frequency located in the middle of
respective carrier frequency of the reception signals and the image
signals of transmission signals, both of which the digital GCA 17
outputs at the IF A, and the image signals of the transmission
signals are converted into a baseband of image signals by the
quadrature detector 18.
Further, the radio equipment of this embodiment is characterized in
that reception signals having the IF A are converted into reception
signals having an IF E by the quadrature detector 18, so that the
reception signals having the IF E are converted into a baseband of
reception signals by a frequency converter 32, instead of the
frequency converter 19, in which the frequency converter 32 is
provided with a quadrature carrier oscillator for outputting
complex local signals having a seventh frequency, which is equal to
the carrier frequency of the reception signals having the IF E.
Further, in FIG. 5, components having the same reference numeral
and symbol as in the first example of the first embodiment perform
the same operation as ones mentioned in the first example of the
first embodiment, and thus their description is omitted here.
Referring to FIG. 5, the radio equipment is designed so that
reception signals and image signals of transmission signals which a
digital GCA 17 outputs at the IF A are input into the quadrature
detector 18 having a quadrature carrier oscillator for outputting
complex local signals having a sixth frequency equal to the carrier
frequency of the image signals, so that at least image signals of
transmission signals are directly converted into a baseband of
image signals, and then the baseband of image signals are input
into a characteristic compensator 22 and an ALC circuit 29.
Reception signals having the IF A are converted into reception
signals having an IF E by the quadrature detector 18, so that the
reception signals having the IF E are converted into a baseband of
reception signals by a frequency converter 32 having a quadrature
carrier oscillator for outputting complex local signals having a
seventh frequency equal to the carrier frequency of the reception
signals having the IF E.
Further, as for the frequency converter 32, the frequency converter
32 includes a quadrature carrier oscillator 7a for outputting
complex local signals having a seventh frequency equal to the
carrier frequency of the reception signals having the IF E,
multipliers 7b and 7c for multiplying real-axis signals and
imaginary-axis signals, which the quadrature detector 18 outputs,
by real-axis signals "cos" of the seventh frequency of local
signals which the quadrature carrier oscillator 7a outputs, and by
imaginary-axis signals "-sin" which have a phase forwarded by 90
degrees relative to that of the real-axis signals, a subtracter 7d
for subtracting outputs of the multiplier 7c from outputs of the
multiplier 7b and taking the subtracted results as outputs of the
real-axis signals, multipliers 7e and 7f for multiplying real-axis
signals and imaginary-axis signals, which the quadrature detector
18 outputs, by imaginary-axis signals "-sin" and real-axis signals
"cos" of the local signals which the quadrature carrier oscillator
7a outputs at the seventh frequency, and an adder 7g for adding
outputs of the multiplier 7f to outputs of the multiplier 7e and
taking the added results as outputs of the imaginary-axis signals.
The frequency converter 32 converts the reception signals, which
the quadrature detector 18 outputs at the IF E, into a baseband of
reception signals.
Subsequently, using the radio equipment of the present embodiment
for compensating transmission signals as described above, a
detailed description will be made with reference to a schematic
diagram regarding a structure in which transmission signals
transmitted from the antenna 3 are input as reference signals into
the characteristic compensator 22 and the ALC circuit 29.
FIG. 6 is a schematic diagram for describing a structure in which
transmission signals transmitted from the antenna 3 are obtained as
reference signals at the characteristic compensator 22, and
illustrates, similar to FIG. 2, transmission signals having a
frequency of 835 [MHz], reception signals having a frequency of 870
[MHz], and local signals output from the carrier oscillator 13
having a first frequency of 848.5 [MHz].
As illustrated in FIG. 6(a), when the transmission signals are
input into the mixer 14 at the carrier frequency of 835 [MHz] and
when the reception signals are input into the mixer 14 at the
carrier frequency of 870 [MHz], both of the transmission and
reception signals are frequency-converted by the local signals,
which the carrier oscillator 13 outputs at the frequency of 848.5
[MHz], so that reception signals having the IF of 21.5 [MHz] and
image signals having the IF of 13.5 [MHz] and generated from the
transmission signals are output from the mixer 14, as illustrated
in FIG. 6(b). Further, when the reception signals having the IF of
21.5 [MHz] and the image signals having the IF of 13.5 [MHz] and
generated from the transmission signals are input into the
quadrature detector 18, in which the complex local signals output
from the quadrature carrier oscillator 6a are set to have a
frequency of 13.5 [MHz], reception signals having the IF of 8.0
[MHz] and the image signals having the IF of 0 [MHz] on a direct
current component having a frequency of zero and generated from the
transmission signals, are output as outputs of the quadrature
detector 18, as illustrated in FIG. 6(c).
Therefore, the reception signals having the IF of 8.0 [MHz] can be
converted into a baseband of reception signals by the frequency
converter 32 in which the quadrature carrier oscillator 7a outputs
the complex local signals at the frequency of 8.0 [MHz].
As described above, in the third example of the first embodiment
(FIG. 5), the quadrature carrier oscillator 1a,which is provided to
the quadrature detector 18 on the side of the receiver 1 of the
radio equipment , which has been described in the first example of
the first embodiment, is modified into the quadrature carrier
oscillator 6a, and the image signals of transmission signals output
from the mixer 14 are directly converted into the baseband signals.
Therefore, while characteristics of the transmission signals are
obtained, the number of times for frequency conversion can be
decreased and signal characteristics including the level and
distortion of the transmission signals can be exactly
compensated.
D. Fourth Example of the First Embodiment
FIG. 7 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a fourth
example of the first embodiment of the present invention.
In FIG. 7, the radio equipment for compensating transmission
signals is characterized in that the frequency converter 32 on the
side of the receiver 1 of the radio equipment, which has been
described in the third example of the first embodiment, has been
omitted, the quadrature detector 18 on the side of the receiver 1
is provided with a quadrature carrier oscillator 8a for outputting
complex local signals having a eighth frequency equal to the
carrier frequency which the image signals of the transmission
signals output from the digital GCA 17 have, instead of the
quadrature carrier oscillator 6a for outputting the complex local
signals having the sixth frequency equal to the carrier frequency
which the image signals of the transmission signals output from the
digital GCA 17 have, and reception signals having the IF A are
converted into a baseband of image signals by the quadrature
detector 18.
Further, the radio equipment of this embodiment is characterized in
that image signals of transmission signals are converted into image
signals having the IF F by the quadrature detector 18, and thus the
characteristic compensator 22 is removed, and in that without
compensating distortion of phase and amplitude of the transmission
signals caused by the baseband of image signals, only a mean level
of the transmission signals is detected by the ALC circuit 29 and
only a level of the transmission signals is controlled through a
feedback control of the analog GCA 27. Further, in FIG. 7,
components having the same reference numeral and symbol as in the
first example of the first embodiment perform the same operation as
ones mentioned in the first example of the first embodiment, and
thus a description of these components is omitted here.
Referring to FIG. 7, the radio equipment is designed so that
reception signals and image signals of transmission signals which
the digital GCA 17 outputs at the IF A are input into the
quadrature detector 18 having a quadrature carrier oscillator for
outputting complex local signals having a eighth frequency equal to
the carrier frequency of the reception signals having the IF A, so
that at least reception signals having the IF A are directly
converted into a baseband of reception signals.
The image signals of the transmission are converted into image
signals having the IF F by the quadrature detector 18, so that the
converted image signals are input into the ALC circuit 29 as they
are. In the ALC circuit 29, a mean level of the transmission
signals transmitted from the antenna 3 is detected using the image
signals having the IF F as reference signals, and the detected mean
level is controlled to be fed back to the analog GCA 27 to
uniformly maintain the detected mean level. In addition, in the
process of digital signals, a level of the digital signals is
detected by calculating a sum of two squares of real-axis signals
and imaginary-axis signals of input complex signals, so that the
mean level of the transmission signals can be detected even when
the image signals having the IF F are used as reference signals as
they are.
Subsequently, using the radio equipment of the present embodiment
as described above, a detailed description will be made with
reference to a schematic diagram regarding a structure in which
transmission signals transmitted from the antenna 3 are input as
reference signals into the ALC circuit 29.
FIG. 8 is a schematic diagram for describing a structure in which
transmission signals transmitted from the antenna 3 are obtained as
reference signals at the ALC circuit 29, and illustrates, similar
to FIGS. 2 and 6, transmission signals having a frequency of 835
[MHz], reception signals having a frequency of 870 [MHz], and local
signals output from the carrier oscillator 13 having a first
frequency of 848.5 [MHz].
As illustrated in FIG. 8(a), when the transmission signals are
input into the mixer 14 at the carrier frequency of 835 [MHz] and
when the reception signals are input into the mixer 14 at the
carrier frequency of 870 [MHz], both of the transmission and
reception signals are frequency-converted by local signals which
the carrier oscillator 13 outputs at the frequency of 848.5 [MHz],
so that reception signals having the IF of 21.5 [MHz] and image
signals having the IF of 13.5 [MHz] and generated from the
transmission signals are output from the mixer 14, as illustrated
in FIG. 8(b). Further, when the reception signals having the IF of
21.5 [MHz] and the image signals having the IF of 13.5 [MHz] and
generated from the transmission signals are input into the
quadrature detector 18, in which the complex local signals output
from the quadrature carrier oscillator 6a are set to have a
frequency of 13.5 [MHz], image signals having the IF of -8.0 [MHz]
and generated from the transmission signals and the reception
signals having the IF of 0 [MHz] on a direct current component
having a frequency of zero are output as outputs of the quadrature
detector 18, as illustrated in FIG. 8(c).
Therefore, the ALC circuit 29 detects the mean level of the
transmission signals using the image signals having the IF of -8.0
[MHz] as they are.
As described above, in the fourth example of the first embodiment,
the frequency converter 32 on the side of the receiver 1 of the
radio equipment, which has been described in the third example of
the first embodiment, is removed, and the reception signals having
the IF A and output from the digital GCA 17 are directly converted
into a baseband of signals by the quadrature detector 18, which
includes a quadrature carrier oscillator 8a for outputting complex
local signals having a eighth frequency equal to the carrier
frequency of the reception signals having the IF A. Therefore, when
only the level of the transmission signals is compensated, a change
of the level of the transmission signals is detected from the image
signals in a state of the IF, and the compensator compensates the
level of the transmission signals. As a result, the process for
changing the transmission signals into the baseband is eliminated
and thus a circuit construction can be simplified.
II. Second Embodiment
Subsequently, a description will be made regarding a second
embodiment with reference to the drawings
A. First Example of the Second Embodiment
FIG. 9 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a first
example of a second embodiment of the present invention. In FIG. 9,
the radio equipment for compensating transmission signals is
characterized in that the mixer 14 of the radio equipment, which
has been described in the first example of the first embodiment, is
changed into a quadrature detector 33 having a quadrature carrier
oscillator for outputting complex local signals having a first
frequency. Further, in FIG. 9, components having the same reference
numeral and symbol as in the first example of the first embodiment
perform the same operation as ones mentioned in the first example
of the first embodiment, and thus a description of these components
is omitted here.
With reference to FIG. 9, to extract desired signals having a
carrier frequency from a predetermined frequency band of signals
which a reception filter 12 outputs, and to quantize (i.e., perform
A/D conversion of) the extracted signals, by a quadrature detector
33 having a quadrature carrier oscillator for outputting complex
local signals having a first frequency, the signals are converted
into complex signals having an IF. With respect to respective
real-axis signals and imaginary-axis signals of the complex signals
having the IF, low-pass filters 34 and 35 impose band limitations
on the complex signals output from quadrature detector 33 at a
frequency less than half of a sampling frequency for
quantization.
Further, when the complex signals are band-limited by the low-pass
filters 34 and 35, a receiver 1 changes the respective real-axis
signals and imaginary-axis signals of the complex signals
band-limited by the low-pass filters 34 and 35 into digital ones,
using ADCs (A/D converters) 36 and 37 for quantizing input signals
at the sampling frequency corresponding to a bandwidth of the
low-pass filters 34 and 35 according to the sampling theorem.
The quantized complex signals output from the ADCs 36 and 37 are
converted into complex signals having a uniform level by GCAs 38
and 39, which maintain output signals at a uniform level by
controlling a degree of amplification to amplify input signals.
Further, the complex signals, which the digital GCAs 38 and 39
output, contain reception signals and image signals of transmission
signals, both of which have the IF A and are represented as a
complex number. The receiver 1 converts the reception signals and
the image signals of the transmission signals into reception
signals having an IF B and image signals having an IF C, both of
which are represented as a complex number and have positive and
negative carrier frequencies symmetrical to a direct current
component having a frequency of zero, by a frequency converter 40
having a quadrature carrier oscillator for outputting complex local
signals at a second frequency located at the middle of each carrier
frequency. The reception signals having the IF B are converted into
a baseband of reception signals by a frequency converter 19 having
a quadrature carrier oscillator for outputting complex local
signals having a third frequency which is equal to the carrier
frequency of the reception signals having the IF B.
Further, the transmitter 2 converts image signals, which the
frequency convert 40 outputs at the IF C, into a baseband of image
signals, by a frequency converter 21, in which complex codomain
signals of the complex local signals, which the quadrature carrier
oscillator 2a of the frequency converter 19 outputs at the third
frequency, are taken as local signals having a fourth
frequency.
In this manner, the radio equipment for compensating transmission
signals directly acquires image signals of the transmission signals
in a state of complex signals.
Further, the quadrature detector 33 includes a quadrature carrier
oscillator 9a for outputting complex local signals having a first
frequency, and multipliers 9b and 9c for multiplying real signals,
which the reception filter 12 outputs, by real-axis signals "cos"
of local signals which the quadrature carrier oscillator 9a outputs
at the first frequency, and by imaginary-axis signals "-sin" which
have a phase forwarded by 90 degrees relative to that of the
real-axis signals, respectively. The quadrature detector 33 obtains
complex number signals by performing orthogonal transformation to
the real signals which the reception filter 12 outputs.
The frequency converter 40 includes the quadrature carrier
oscillator 1a for outputting complex local signals having the
second frequency which is located at the middle of respective
carrier frequency of the reception signals and the image signals of
the transmission signals, both of which the digital GCAs 38 and 39
output at the IF A represented as a complex number, and multipliers
10b and a multiplier 10c for multiplying real and imaginary-axis
signals of the complex signals, which the digital GCAs 38 and 39
output, by real-axis signals "cos" of local signals which the
quadrature carrier oscillator 1a outputs at the second frequency,
and by imaginary-axis signals "-sin" which have a phase forwarded
by 90 degrees relative to that of the real-axis signals,
respectively. A subtracter 10d for subtracts outputs of the
multiplier 10c from outputs of the multiplier 10b and takes the
subtracted results as outputs of the real-axis signals, multipliers
10e and 10f multiply real and imaginary-axis signals of the complex
signals, which the digital GCAs 38 and 39 output, by imaginary-axis
signals "-sin" and real-axis signals "cos", respectively, of local
signals which the quadrature carrier oscillator 1a outputs at the
second frequency, and an adder 10g for adds outputs of the
multiplier 10f to outputs of the multiplier 10e and taking the
added results as outputs of the imaginary-axis signals. The
frequency converter 40 performs frequency conversion of the
reception signals and the image signals of the transmission
signals, both of which the digital GCAs 38 and 39 output at the IF
A represented as a complex number.
Additionally, when a level of the image signals of the transmission
signals is calculated at the output of the quadrature detector 33,
as illustrated in the schematic diagram of FIG. 10, for example,
when the transmission signals transmitted from the antenna 3 has a
level of 0 [dBm], the antenna sharer (duplexer) 4 has a leakage
electrical power attenuation quantity of 35 [dB], the LNA 11 and
the reception filter 12 have the total gain of 6 [dB], the
quadrature detector 33 has a gain of 3 [dB], and the image signals
of the quadrature detector 33 has a suppressed level of 30 [dB],
the level of the image signals of the transmission signals is
obtained at the output of the quadrature detector 33 by the
following Equation 2.
Equation 2 0 [dBm]-35 [dB]+6 [dB]+3 [dB]-30 [dB]=-56 [dB] (2)
As described above, in FIG. 9, the mixer 14 of the radio equipment
having a function of compensating transmission signals, which has
been described in the first example of the first embodiment, is
changed into the quadrature detector 33, so that the level of the
image signals of the transmission signals can be obtained at a
level without influencing the reception signals. For instance, in
the case of radio equipment in which transmission signal waves and
reception signal waves are easily separated from each other even
when they are overlapped with each other at a frequency of the same
carriers as signals based on a CDMA (Code Division Multiple Access)
or TDD mode, the reception signals and the image signals of the
transmission signals, both of which have the first IF, are
extracted by the same frequency, so that the number of times for
performing frequency conversion can be reduced in the following
processes, and thus a circuit construction can be simplified.
B. Second to Fourth Examples of the Second Embodiment
In the second embodiment, as in the second to fourth examples of
the first embodiment which have been described using FIGS. 4 to 8
in the first embodiment, the frequency converter 19 and the
frequency converter 21 shown in FIG. 9 may be changed into a
synthetic frequency converter 20 (second example of the second
embodiment), the frequency converter 19 may be changed into a
frequency converter 32, while the frequency converter 21 is removed
(third example of the second embodiment), the frequency converter
19 may be removed together with the frequency converter 21 (fourth
example of the second embodiment).
Further, similar to the quadrature detector 18 described in the
first embodiment, the quadrature carrier oscillator of the
frequency converter 40 uses a quadrature carrier oscillator 1a for
the second example, a quadrature carrier oscillator 6a for the
third example, and a quadrature carrier oscillator 8a for the
fourth example.
Thus, the second to fourth examples of the second embodiment can
get the same effects as in the second to fourth examples of the
first embodiment.
III. Third Embodiment
Herein below, a description will be made regarding a third
embodiment of the present invention with reference to the
drawings.
A. First Example of the Third Embodiment
FIG. 11 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a first
example of the third embodiment of the present invention. In FIG.
11, the radio equipment is characterized in that, in the radio
equipment, which has been described in the first example of the
first embodiment, the transmission signals input toward the
receiver 1 are not obtained as the leakage electrical power from
the transmitter-sided input terminal 4z of the antenna sharer 4 to
the receiver-sided output terminal 4y, but are explicitly obtained
using a transmission signal separator for separating a part of the
electrical power of the transmission signals and a mixer for mixing
the separated transmission signals with the reception signals.
Further, in FIG. 11, components having the same reference numeral
and symbol as in the first example of the first embodiment perform
the same operation as ones mentioned in the first example of the
first embodiment, and thus their description is omitted here.
With reference to FIG. 11, the radio equipment inserts a
directional coupler 41 between the PA 28 and the transmitter-sided
input terminal 4z of the antenna sharer 4, and inputs the
transmission signals output from the PA 28 into an input terminal
41x of the directional coupler 41 in order to transmit the
transmission signals to the antenna 3. In the directional coupler
41, some parts of input transmission signals are separated and
output from a separation output terminal 41y, most remaining
transmission signals are output from an output terminal 41z. The
transmission signals, which are output from the output terminal 41z
of the directional coupler 41, are sent from the transmitter-sided
input terminal 4z of the antenna sharer 4 connected to the output
terminal 41z of the directional coupler 41 through the antenna
connection terminal 4x to the antenna 3, and transmitted to other
radio equipment.
Some parts of the transmission signals, which are output from the
separation output terminal 41y of the directional coupler 41, are
input through an ATT 42 for attenuating and outputting input
electrical power and a switch 43 toward the receiver 1.
In the receiver 1, a mixer 44 is inserted between the reception
filter 12 and the mixer 14, both of which have been mentioned in
the first example of the first embodiment. The mixer 44 mixes the
signals from the reception filter 12 with the transmission signals
output from the switch 43 and outputs the mixed results to the
mixer 14.
Therefore, the radio equipment for compensating transmission
signals according to the present embodiment is designed so that,
when a frequency characteristic is bad on a communication band edge
or when the leakage electrical power of the antenna sharer is small
due to an available frequency band in a multi-band radio equipment,
the switch 43 is closed and then the transmission signals separated
by the directional coupler 41 are input toward the receiver 1 by
the mixer 44 and are obtained at a proper level on the side of the
receiver 1. Further, in the other cases, the transmission signals
are obtained at a proper level using the antenna sharer 4.
Further, the transmission signals separated by the directional
coupler 41 are input toward the receiver 1 by the mixer 44 at any
time without the switch 43.
Additionally, when a level of the image signals of the transmission
signals is calculated at the output of the mixer 14, as shown in
the schematic diagram of FIG. 12, for example, when the
transmission signals transmitted from the antenna 3 has a level of
0 [dBm], the directional coupler 41 has a combination degree of 20
[dB], the mixer 44 has a loss of 0 [dB], the mixer 14 has a gain of
3 [dB], and the image signals of the mixer 14 has a suppressed
level of 0 [dB]. When the ATT 42 is used without any insertion, the
level of the image signals of the transmission signals is obtained
at the output of the mixer 14 by the following Equation 3.
Equation 3 0 [dBm]-20 [dB]-0 +[dB]+3 [dB]-0 [dB]=-17 [dB] (3)
Thus, it is preferable to insert and use the ATT 42.
As described above, the first example of the third embodiment is
designed so that, in the radio equipment having a function of
compensating transmission signals which has been described in the
first example of the first embodiment, the transmission signals
input toward the receiver 1 are not obtained as the leakage
electrical power from the transmitter-sided input terminal 4z of
the antenna sharer 4 to the receiver-sided output terminal 4y. The
radio equipment of the first example of the third embodiment
includes the direction coupler 41 for separating a part of the
electrical power of the transmission signals, the mixer 44 for
mixing the separated transmission signals with the reception
signals and the switch 43 for opening and closing between the
directional coupler 41 and the mixer 43. When the transmission
signals input toward the receiver 1 have a low level, the switch 43
is closed and then the transmission signals separated by the
directional coupler 41 are input toward the receiver 1 by the mixer
44 and are obtained at a proper level on the side of the receiver
1. Further, in the other cases, the transmission signals are
obtained at a proper level using the antenna sharer 4. Under any
circumstances, proper transmission signals can be input toward the
receiver.
B. Second to Fourth Examples of the Third Embodiment
In the third embodiment, as in the second to fourth examples of the
first embodiment which have been described using FIGS. 4 to 8 in
the first embodiment, the frequency converter 19 and the frequency
converter 21 shown in FIG. 11 in the first example of the third
embodiment may be changed into a synthetic frequency converter 30
(second example of the third embodiment), the frequency converter
19 may be changed into a frequency converter 32, while the
frequency converter 21 is removed (third example of the third
embodiment), the frequency converter 19 may be removed together
with the frequency converter 21 (fourth example of the third
embodiment).
Further, as described in the first embodiment, the quadrature
carrier oscillator of the quadrature detector 18 is adapted to make
use of a quadrature carrier oscillator 1a for the second example, a
quadrature carrier oscillator 6a for the third example, and a
quadrature carrier oscillator 8a for the fourth example.
Thus, the second to fourth examples of the third embodiment can get
the same effects as in the second to fourth examples of the first
embodiment.
IV. Fourth Embodiment
Finally, a description will be made regarding a fourth embodiment
of the present invention with reference to the drawings.
A. First Example of the Fourth Embodiment
FIG. 13 is a block diagram illustrating radio equipment for
compensating transmission signals in accordance with a first
example of the fourth embodiment of the present invention. In the
present embodiment, the radio equipment having a function of
compensating transmission signals is characterized in that, in the
radio equipment having a function of compensating transmission
signals which has been described in the first example of the first
embodiment, the transmission signals input toward the receiver 1
are not obtained as the leakage electrical power from the
transmitter-sided input terminal 4z of the antenna sharer 4 to the
receiver-sided output terminal 4y, but are explicitly obtained
using a transmission signal separator for separating a part of the
electrical power of the transmission signals and a mixer for mixing
the separated transmission signals with the reception signals.
Further, in FIG. 13, components having the same reference numeral
and symbol as in the first example of the first embodiment and as
in the first example of the second embodiment perform the same
operation as ones mentioned in the first example of the first
embodiment and in first example of the second embodiment, and thus
their description is omitted here.
Referring to FIG. 13, the radio equipment inserts a directional
coupler 41 between the PA 28 and the transmitter-sided input
terminal 4z of the antenna sharer 4, and inputs the transmission
signals output from the PA 28 into an input terminal 41x of the
directional coupler 41 in order to transmit the transmission
signals to the antenna 3. Similar to the third embodiment, in the
directional coupler 41, some parts of input transmission signals
are separated and output from a separation output terminal 41y,
most remaining transmission signals are output from an output
terminal 41z. Some parts of the transmission signals, which are
output from the separation output terminal 41y of the directional
coupler 41, are input through an ATT 42 and a switch 43 toward the
receiver 1.
In the receiver 1, a mixer 44 is inserted between the reception
filter 12 and the mixer 14 of the radio equipment having a function
for compensating transmission signals which has been mentioned in
the first example of the second embodiment. The mixer 44 mixes the
signals from the reception filter 12 with the transmission signals
output from the switch 43, and then outputs the mixed results to
the quadrature detector 33.
Therefore, the radio equipment in FIG. 13 is designed so that, when
a frequency characteristic is bad on a communication band edge or
when the leakage electrical power of the antenna sharer is small
due to an available frequency band in a multi-band radio equipment,
the switch 43 is closed, and then the transmission signals
separated by the directional coupler 41 are input toward the
receiver 1 by the mixer 44 and are obtained at a proper level on
the side of the receiver 1. Further, in the other cases, the
transmission signals are obtained at a proper level using the
antenna sharer 4.
Further, similar to the third embodiment, it does not matter that
the transmission signals separated by the directional coupler 41
are input toward the receiver 1 by the mixer 44 at any time without
the switch 43.
Additionally, in the present embodiment, when a level of the image
signals of the transmission signals is calculated at the output of
the quadrature detector 33, as shown in the schematic diagram of
FIG. 14, for example, when the transmission signals transmitted
from the antenna 3 has a level of 0 [dBm], the directional coupler
41 has a combination degree of 20 [dB], the mixer 44 has a loss of
0 [dB], the quadrature detector 33 has a gain of 3 [dB], and the
image signals of the quadrature detector 33 has a suppressed level
of 0 [dB], the level of the image signals of the transmission
signals is obtained at the output of the quadrature detector 33 by
the following Equation 4.
Equation 4 0 [dBm]-20 [dB]-0 [dB]+3 [dB]-30 [dB]=-47 [dB] (4)
Thus, it is unnecessary to insert and use the ATT 42 at all
times.
As described above, the first example of the fourth embodiment is
designed so that, in the radio equipment having a function of
compensating transmission signals, which has been described in the
first example of the second embodiment, the transmission signals
input toward the receiver 1 are not obtained as the leakage
electrical power from the transmitter-sided input terminal 4z of
the antenna sharer 4 to the receiver-sided output terminal 4y. The
radio equipment of the first example of the fourth embodiment
includes the direction coupler 41 for separating a part of the
electrical power of the transmission signals, the mixer 44 for
mixing the separated transmission signals with the reception
signals and the switch 43 for opening and closing between the
directional coupler 41 and the mixer 43. When the transmission
signals input toward the receiver 1 has a low level, the switch 43
is closed, and then the transmission signals separated by the
directional coupler 41 are input toward the receiver 1 by the mixer
44 and are obtained at a proper level on the side of the receiver
1. Further, in the other cases, the transmission signals are
obtained at a proper level using the antenna sharer 4. Under any
circumstances, the transmission signals can be input toward the
receiver at a proper level.
B. Second to Fourth Examples of the Fourth Embodiment
In the fourth embodiment, as in the second to fourth examples of
the first embodiment, which have been described using FIGS. 4 to 8
in the first embodiment, the frequency converter 19 and the
frequency converter 21 shown in FIG. 13 in the first example of the
fourth embodiment may be changed into a synthetic frequency
converter 30 (second example of the fourth embodiment), the
frequency converter 19 may be changed into a frequency converter
32, while the frequency converter 21 is removed (third example of
the fourth embodiment), the frequency converter 19 may be removed
together with the frequency converter 21 (fourth example of the
fourth embodiment).
Further, similar to the quadrature detector 18 described in the
first embodiment, the quadrature carrier oscillator of the
frequency converter 40 is adapted to make use of a quadrature
carrier oscillator 1a for the second example, a quadrature carrier
oscillator 6a for the third example, and a quadrature carrier
oscillator 8a for the fourth example, respectively.
Thus, the second to fourth examples of the fourth embodiment can
accomplish the same effects as in the second to fourth examples of
the first embodiment.
Furthermore, it is described in the first examples of the first to
fourth embodiments that the quadrature carrier oscillator 2a is
provided on the side of the frequency converter 19, and that the
frequency converter 21 generates the complex codomain signals of
the complex local signals which the quadrature carrier oscillator
2a outputs, by inverting the sign of the imaginary-axis signals of
the complex local signals which the quadrature carrier oscillator
2a outputs using the sign inverter 3a, and uses the generated
signals as the local signals. However, it does not matter that the
quadrature carrier oscillator is provided on the side of the
frequency converter 21, and that the frequency converter 19
generates the complex codomain signals of the complex local signals
which the quadrature carrier oscillator on the side of the
frequency converter 21 outputs by mean of the sign inverter, and
uses the generated signals as the local signals.
According to the present invention, the transmission signals, which
are obtained on the side of the receiver by the transmission signal
distributor, are extracted as the image signals having the carrier
frequency around the first IF of the reception signals by the first
frequency converter, so that without an additional new circuit
construction for extracting separate transmission signals, the
characteristics of the transmission signals can be compensated
using the image signals as reference signals. Thus, it is possible
to implement the radio equipment having a function of compensating
transmission signals, which is particularly suitable for
transmitting and receiving the signals based on the FDD mode, and
effectively compensates level and linearity of the transmission
signals.
* * * * *